1. Field of the Invention
The present invention relates to fluid transfer apparatus for introducing sterile liquid or the like into a vessel at a controlled rate.
2. Description of the Prior Art
The pharmacies of large hospitals are often called upon to provide many doses of a particular medicament or drug within a relatively short period of time. Such drugs are commonly provided by drug companies in rubber stoppered vials in dry or lyophilized powder form. It is necessary for the pharmacy to fill the vials to a predetermined level with a sterile liquid to dissolve the powder for administration of the drug through the usual intravenous or IV equipment.
A means is necessary for rapidly and efficiently injecting sterile liquid successively into a plurality of stoppered vials, and without contamination of the contents of the vial, such as would occur if the stopper were removed and the sterile liquid simply poured into the vial.
Various prior art fluid transfer means for filling such drug vials have been advanced. In one system the rubber stopper of the vial includes a ridge to show where the filling needle is to be inserted, and another to indicate where a vent needle is to be inserted. A predetermined quantity of the sterile liquid is then gravity fed into the vial through the filling needle. This proved to be extremely time consuming because both the filling and vent needles had to be separately withdrawn from each vial and reinserted into the next vial, all the while shifting the filling equipment down the line of vials to be filled.
In another prior art system, the sterile liquid was introduced into the vial under pressure by a syringe. However, this left a residual pressure in the vial which adversely affected subsequent precision dispensing of drugs from the vial. This problem of residual pressure was eliminated by yet other systems employing a filling needle having a venting passage. U.S. Pat. Nos. 3,941,171, issued Mar. 2, 1976 and 4,058,121, issued Nov. 15, 1977 are typical of these types of system.
In the first of these patents the opposite extremities of a filling needle were inserted into a filled vial and an empty vial, respectively, the empty vial venting into the filled vial as the filling process took place. This gravity feed principal was undesirably slow. In the second patent, a filling needle was used to vent the vial as filling took place, but the sterile liquid injected was drawn periodically from a conventional syringe. This involved a number of tedious and repetitive steps ill suited for rapidly filling large numbers of vials. Also, the capacity of the syringe was such that it had to be replenished quite often by withdrawal of liquid from some larger fluid source. When this was done atmospheric air would flow through the needle vent passage into the fluid source container, necessitating a contaminant filter in the passage to prevent contamination of the sterile liquid. Finally, the syringe was not well suited to sensitive control of the rate of filling of a vial.
A problem not met by the devices of the prior art is the frequent need to fill successive stoppered vials containing different medications with solution. Previously, in order to avoid cross-contamination, different fluid transfer apparatuses had to be substituted between batches of different medications.